Content for  TS 24.186  Word version:  18.0.0

If the terminating UE determines that the UE and the network supports the IMS data channel, when the UE receives the re-INVITE request with an SDP offer, which includes the bootstrap data channel media descriptions, i.e. the "m=" line containing the media set to "application", the UDP port number, the proto value set to "UDP/DTLS/SCTP" and the fmt value set to "webrtc-datachannel" and with associated "dcmap" attribute lines containing a subprotocol parameter set to "http" and any "stream-id" parameter set to values 0, 10, 100 or 110, the procedure defined in clause 9.3.3.1.2 applies. If the terminating UE wants to setup a bootstrap data channel during the session modification by sending SIP re-INVITE request, the procedure defined in clause 9.3.2.1.3.1 applies.

If the terminating UE has an established bootstrap data channel associated with the MMTel session available and if the UE receives the re-INVITE request with an SDP offer which includes data channel media descriptions for the bootstrap data channel, as well as the requested application data channel and the associated data channel application binding information (provided within the "a=3gpp-req-app" SDP attribute), and the terminating UE accepts the offered application data channel, it shall return a 183 (Session Progress) or 200 (OK) response to the re-INVITE request with the generated the SDP answer based on the TS 26.114 and RFC 8864. If the terminating UE wants to setup an application data channel, the procedure defined in clause 9.3.2.1.3.2 applies.

If the IMS AS received from the originating network a re-INVITE request with the SDP offer containing data channel media description for the bootstrap data channel establishment, the procedure defined in clause 9.3.3.2.1 applies. If the IMS AS received from the served user a re-INVITE request with the SDP offer containing data channel media description for the bootstrap data channel establishment, the procedure defined in clause 9.3.2.2.2.1 applies.

Upon receipt of a re-INVITE request with the SDP offer including a new application data channel media description(the media line with the "dcmap" attribute containing "stream-id" parameter set to values starting at 1000) along with the video, audio, and bootstrap data channel media descriptions from the originating network, the IMS AS shall notify the DCSF about the media change request and request MF to update the media resources. Based on the response on the data channel media resource update from the MF and media instruction from DCSF as specified in 3GPP TS 29.175 [18], the IMS AS shall:

1. delete the data channel media description (media line with the "dcmap" attribute containing "stream-id" parameter set to the values starting at 1000 and "a=3gpp-req-app" attribute with "endpoint" parameter set to value "server") if the media instruction from DCSF is to terminate the media;
2. delete the data channel media description if the media instruction from DCSF is to reject the media as specified in 3GPP TS 29.175 [18];
3. modify the data channel media description if the media instruction from DCSF is to terminate and originate the media:
   • replace the DC endpoint information in the SDP offer with the media resource information on the termination towards to the terminating UE allocated by the MF;
4. generate and add a data channel media description (media line with the "dcmap" attribute containing "stream-id" parameter set to values starting at 1000 and "a=3gpp-req-app" attribute with "endpoint" parameter set to value "server") if the media instruction from DCSF is to originate a new media as specified in 3GPP TS 29.175 [18];

Upon receipt of the re-INVITE request with an SDP offer which contains an existing application data channel media description in which the a new "a=dcmap" line containing the "stream-id" parameter value set to values starting at 1000 is added, the IMS AS shall notify the DCSF about media change request, and request MF to update the media resource if the media instruction from DCSF is to update the media. Upon receipt of the 200 (OK) response on the re-INVITE request with the SDP answer which contains media description of the requested application data channel from terminating UE, the IMS AS shall notify the DCSF about media change success or media change failure and request the MF to update or release the media resources. The IMS AS shall modify the application data channel media description in the SDP answer and send 200 (OK) response to S-CSCF with the modified SDP answer for the requested application data channel as well as the media descriptions of established video, audio, and bootstrap data channels. Upon receiving the re-INVITE request from the terminating UE to setup an application data channels and the corresponding 200 (OK) response form the originating network, the procedure in clause 9.3.2.2.2.2 applies.

Upon receipt of the re-INVITE request with an SDP offer which contains an existing application data channel media description in which the UDP port number is set to 0, the IMS AS shall notify the DCSF about media change request, and request the MF to release the corresponding media resource if the media instruction from DCSF is to delete the media. Upon receipt of the re-INVITE request with an SDP offer which contains an existing application data channel media description in which an existing "a=dcmap" line is removed, the IMS AS shall notify the DCSF about media change request, and request MF to update the media resource if the media instruction from DCSF is to update the media. Upon receipt of the 200 (OK) response on the re-INVITE message with the SDP answer, the procedure in clause 9.3.3.2.2.2 applies. Upon receiving the re-INVITE request from the terminating UE to close an application data channels and the corresponding 200 (OK) response form the originating network, the procedure in clause 9.3.2.2.2.3 applies.